For all of you interested in how to interface a Thermistor with an Arduino, you have come to the right place!
Truthfully, this is not a new topic, nor is it Rocket Science, but for any beginners out there wanting to learn about the Secret Life of Thermistors. this post will hopefully help.
The word "Thermistor" is a portmanteau of "Thermal" and "Resistor," and as it's name suggests, it is a resistor who's resistance changes with temperature. Now, the truth of the matter is that all conductors are thermistors, because resistance is a function of temperature, to varying degrees and directions depending on the materials making up the conductor.
A Thermistor, however, is commonly understood to be a device where such temperature effects are deliberately exaggerated, easily observable, and optimized for specific applications. Depending on the material formulation of it's body, Its resistance can be made to change either positively (increasing resistance with increasing temperature) or negatively (decreasing resistance with increasing temperature), known as PTC or NTC types, respectively.
Thermistors have the advantage of being inexpensive and rugged, but suffer from a highly non-linear change in resistance with temperature. In other words, there is not a one-to-one relationship between temperature and resistance changes. This is a manageable problem in most applications, and this project explains the implications.
Here is a typical Thermistor used for temperature measurement (The very one used in this project, in fact!)
http://www.adafruit.com/products/372
Rather than repeating all the details here, I will direct you instead to the place where the project lives:
https://github.com/EasternStarGeek/Fun-with-Thermistors
For those of you unfamiliar with Git Hub, it is an on-line repository for projects, providing storage, as well as a mechanism for several people to collaborate on the same project.
To examine or download this project, click the link above, and look at the README file. To download everything, click the Download link. You will be able to download an archive of everything you need, including a schematic, code example and supporting documents.
Have fun!
